The charity, which questioned 2,000 people aged 65 and over, estimates that around 200,000 elderly people will spend the holiday alone this year.
And those who have recently been widowed struggle the most during the season.
The research revealed that more than three-quarters (77 per cent) of over 65's believe the first Christmas after losing someone you love is the hardest, with up to 170,000 older people soon to face their first Christmas without their spouse.
Similarly, over 750,000 older widowed people often feel more lonely over Christmas than at any other time of the year.
In total, Age UK estimates that more than three million older people may not be looking forward to the festive season, 700,000 (23 per cent) of whom say this is because it brings back too many memories of people who have passed away and of happier times.
To help combat loneliness among the elderly this Christmas, the charity is launching a campaign titled "No one should have no one to turn to" and is calling on the public for support.
The campaign aims to encourage people to reach out to lonely elderly people in their community and highlights Age UK’s befriending service, where volunteers can visit an older person in their home or accompany them to a social activity.
Speaking about the findings of Age UK’s survey, celebrity ambassador Dame Helen Mirren said: “Getting older brings new challenges – receiving a life-threatening diagnosis like dementia, losing the person who's been your rock your whole life or struggling to manage the stairs in the only place that feels like home.
“To make matters worse, so many who are struggling have nobody to help them.”
The actor added that she supports Age UK “so they can continue to be there for anyone who needs them – even on Christmas day”.
Fellow ambassador, radio presenter Dev Griffin, agreed and called upon members of the public to make a difference.
“We should all be taking a few minutes out of our day to chat to those around you, whether it's your grandad or the older lady at your bus stop,” Griffin said.
“You could be the first person they've spoken to for a long time.“
It isn’t just elderly people who are affected by loneliness. According to the Office for National Statistics (ONS), five per cent of adults in England said they felt lonely “often” or “always” between 2016 and 2017.
Those aged 16 to 24-years-old were also found to experience loneliness more often than those in older age groups; while women, widows, single people, renters and those with poor health were identified as being more susceptible to feelings of isolation.
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